Boletín chileno de parasitología
versión impresa ISSN 0365-9402
Bol. chil. parasitol. v.54 n.3-4 Santiago jul. 1999
Hydatidosis in the province of La Pampa, Argentina, 1998.
Roberto Lamberti, Claudio Calvo, Arian Pombar, Lilia Gino, Emiliano Alvarez E, Carlos Aguado y
Faculty of Veterinay Science, La Pampa National University. Calle 5 y 105, (6360) General Pico,
La Pampa, Argentina
Echinococcus granulosus es el agente causal de la hidatidosis clásica o equinococcosis quística. En América del Sur el ciclo mas extendido es el que involucra al perro y la oveja al existir condiciones ideales para la existencia del parásito.
En la Provincia de La Pampa mantiene una presencia endémica con notificación de casos de infección humana y perros infectados con E. granulosus. En el presente trabajo de evalúa la prevalencia y distribución en el Departamento Maracó, Provincia de La Pampa.
Perros de 36 establecimientos ganaderos fueron evaluados con bromhidrato de arecolina a la dosis de 3,5 mg(kg. En 27 establecimientos se detectó Taenia sp. y en tres Echinococcus granulosus.
Se tomaron muestras de sangre de todos los habitantes de los estacimientos ganaderos las que fueron procesadas por enzimoinmunoensayo (ELISA). Asimismo, se efectuó un estudio retrospectivo sobre casos de hidatidosis tratados en el hospital de General Pico y dos clínicas privadas.
Once casos humanos fueron tratados en período 96/97 (tasa de incidencia 6,79 x 100000).
La Provincia de La Pampa parece mantener una presencia endémica con notificación de casos y perros infectados. A consecuencia de ello es de interés sanitario ampliar las investigaciones a otros departamentos provinciales a los efectos de delimitar el área endémica de distribución y organizar sistemas de vigilancia epidemiológica de la enfermedad.
Key words (Palabras clave): hydatidosis (hidatidosis; epimiology (epidemiología); control.
Echinoccocus granulosus is the agent that causes the classical hydatidosis or cystic echinoccosis. This is the most important variety of echinococcosis due to its extended distribution and its high prevalence in human, cattle and dog, either from the view point of sanitary health as well as from economy (Thakur, 1986; Larrieu, 1991; Ruiz et al., 1994).
The parasitone spreads all through South America. However, the most prevailing areas are the rural regions where the sheep breeding is one of the principal economic activities: Argentina, Uruguay, Chile, the South of Brasil and the Peruvian mountain ranges.
The adult stage of E. granulosus lives i the samll instestine of the dog, with its head lodged in the villi. Its length goes from 3 to 6 mm.
The most spread cycle in South America is the sheep-dog cycle, which offers excellent conditions for the development of the parasite.
Hydatidosis presents a higher prevalence in rural areas where the simultaneous presence of dogs and cattle, together with the ignorance and irresponsibility of man, lead to about favorable conditions for the transmission cycle (Thompson and Lymbery, 1995).
As in the province of La Pampa echinococcosis/hydatidosis shows an enzootic presence with notification of human cases, parasitized cattle and infected dogs, the present work has the aim of contributing to the study of the distribution and prevalence of the disease.
MATERIALS AND METHODS
Maracó District is situated in the Nort-West of the Province of La Pampa. Its economy is based mainly o agricultural and livestock activities, specially bovine breeding and, secondarily, ovine.
Thirty six farms that had ovines, were randomly chosen from a total of 440.
The dogs were dosed with arecoline hydrobromide at a dose of 3.5 mg/kg. The animals that did not react were given another dose consisting in 50% of the first one. The samples were collected and analysed in situ by means of a water dilution and a direct observation with a magnifying glass over a dark surface (Schantz, 1973). All the dogs that resulted prosivite were treated with praziquantel at 5 mg/kg.
Blood samples, by means of a digital puncture and absortion of the blood drop in a special filter paper, were taken from all the people living in all the inquired farm (Coltorti et al., 1990). The samples were procesed by the ELISA Technique (Coltorti, 1986; Larrieu et al., 1994).
A retrospective survey on cases of human hydatidosis attended in the Hospital of General Pico, head o the sanitary region, and in two prevate clinisc, was performed.
Twenty two (16.1%) out of 137 dogs evaluated (3.8 specimens per farm), did not defecate. From the remaining 115 individuals 67 (58.3%) were found positive ot Tenia sp. and 3 (2.6%) to E. granulosus (two males and one female). In general, the infections were low. Dogs from 27 (75%) farms resulted positive to Taenia sp. and 3 (8.3%) to E. granulosus.
Sera from 49 inhabitants of those farms. average age 38, were studied, resulting all of them below the cut value (8 SD).
The retrospective analysis from the clinical records of the hospital and the two private clinics indicated 11 cases operate during the period 1996/1997, from which 6 were inhabitants of Maracó District (annual incidence rate of 6.8 x 100,000 inhabitants).
Although hydatidosis in widespread all over Argentina, it has higher endemic levels in the Patagonia and in the provinces of Buenos Aires, Corrientes and Mendoza.
Having human beings in consideration, in Patagonia (Chubut, Neuquen, Rio Negro and Tierra del Fuego) 2,096 new cases have been registered in the period 1984/1988 (annual incidence rate of 41 x 100,000) and 471 new cases in the Province of Buenos Aires in the period (1983/1987 (incidence rate of 0.8 x 100,000). For the period 1988/92 the average annual number of cases for all the country was 464 (national incidence rate of 1.42 x 100,000).
The definitive host, presents high levels of parasitism. The global canine echinoccocic infection rates corresponding to the Patagonia and the province of Buenos Aires fluctuated, before control measures, from 28.2% in Huiliches, Neuquen to 40.2% in Cushamen, Chubut, 41.5% in Norquinco, Rio Negro and 28.2% in Azul, Buenos Aires (Larrieu, 1991; Ruiz et al., 1995).
The province of La Pampa limits with the endemic ecosistems of the Patagonia and Mendoza where the main cattle production is based on ovines and caprines respectively.
Several studies have been performed in order to detemine the prevalence of the parasite in the definitive host. The percentage of infected dogs has been noted as follow: 7.0% (Maracaó, 1982) and 6.3% (Utracan, 1994). The infection in hares has been estimated in 0.43% (Almudevar et al., 1986; Larrieu et al., 1996).
Though with a lower prevalence statistically significative, the results of the present evaluation show a consistency with the situation of hydatidosis in La Pampa. It is a present pathology, that accomplishes its transmission cycle principally with the ovine, certainly not with the bovine which is the most importatn cattle raising production in the region.
Whereas the official hydatidosis notification in the Province of La Pampa gives 36 human cases for the period 1987/1996 (3.6 per year), retrospective surveys show a prevalence significantly higher. For example, only in the Hospital of General Acha 14.5 new cases are treated per year with a regional incidence rate 26.6 x 100.000 inhabitants (Larrieu et al., 1996).
In summary, it is of public health interest to fulfill epdemiological investigations in other districts of the Province of La Pampa with the aim of delimitanting the endemic distribution within its boundaries and also organizing surveillance systems o human hydatidosis.
Echinococcus granulosus is the agent that causes the classical hydatidosis or cystic echinoccosis. The most spread cycle in South America is the sheepdog cycle, and offers favorable conditions for the development of the parasite.
As the province of La Pampa shows an endemic presence with notification of cases and infected dogs, the present work has the aim of contributing to the study of the distribution and prevalence of the disease inthe distritc of Maracó, La Pampa, Argentina.
Dogs of 36 farms that had ovines, were dosed with arecoline hydrobromide at a dose of 3.5 mg/kg. Dogs from 27 (75%) farms resulted positive to Tenia sp. and 3 (8.3%) to E. granulosus.
Blood samples were taken to all the people living in all the inquired farm and were processed by the ELISA test for hydatidosis. A retrospective survey on cases of human hydatidosis attended in the Hospital of General Pico. head if the sanitary region, and in two private clinics was performed.
Analysis of clinical records indicated 11 cases operated during the period 1996/1997 (annual incidence rate of 6.8 x 100,000 inhabitants).
It is of public health interest to fulfill epidemiologic investigations in other districts of the Province of La Pampa with the aim of delimitating the endemic distribution within the province and also organizing surveillance systems o human hydatidosis.
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